This is a competing continuation application to conduct theoretically-driven research to determine the relations between romantic relationships and psychosocial adjustment and mental health. We have been following a sample of 200 youth who were recruited in the 10th grade and have been studied for the last 10 years with a very high retention rate. By the end of this grant period we will have collected 8 waves of data including observations, interviews and questionnaires. Their parents, friends and romantic partners also completed measures about their relationships and mental health. We have examined the youth when they were adolescents (14-19 yrs. old) and emerging adults (20-25 yrs. old). We propose to extend the work to examine the adult years of 26 to 30 years of age, which is the period when relationships typically become more interdependent, with the majority cohabiting or marrying. Our aims are: 1) To examine continuity and change in romantic experiences from adolescence and emerging adulthood into and during adulthood when many become involved in more interdependent relationships, such as cohabitation and marriage; 2) To determine the degree to which past and present romantic experiences affect adjustment, mental health and risk in adulthood, and conversely, how adjustment, mental health and risk affect romantic experiences in adulthood; and 3) To determine the degree to which past romantic experiences, current relationship cognitions, ongoing interpersonal processes, the characteristics of the person and the characteristics of the partner are interrelated and affect the future course of the relationship, adjustment and mental health. To meet these aims, we propose to collect three additional waves of interview, observational and multi-agent questionnaire data, and spaced 18 months apart. We also propose to gather diary data from couples to assess key processes of daily interaction such as support, conflict, jealousy and reactivity. The project is designed to identify risk and protective factors and processes. Thus, it will contribute both to basic theories of psychosocial development and to prevention science.